Pluggable converter modules, such as optoelectronic transceiver modules, are well-known in the computer industry. Conventional optoelectronic transceiver modules are utilized to interconnect circuit cards of communication links and other electronic modules or other subassemblies. Optoelectronic transceiver modules are designed to receive electrical data signals and retransmit these signals as optical signals, and vice versa. Various international and industry standards define the type of connectors used to interface computers to external communication devices, such as modems, network interfaces, and other transceivers. It is desirable to make transceiver modules pluggable so the modules can be easily replaced. It is also desirable to miniaturize transceiver modules in order to increase the port density associated with the network connection (switch boxes, cabling patch panels, wiring closets, computer I/O, etc.).
Numerous standards are known that define form factors for miniaturized electronic devices, such as the Small Form-Factor Pluggable (SFP) standard that specifies an enclosure 9.8 millimeters in height, 13.5 millimeters in width, and a minimum of 20 electrical input/output connections. The specific standards for SFP transceivers are set forth in the “Small Form-Factor Pluggable (SFP) Transceiver Multisource Agreement (MSA),” dated Sep. 14, 2000, which Applicants hereby incorporate by reference. Patents identified by issued U.S. Pat. Nos. 6,570,768, 5,879,173, 5,864,468, 5,734,558, 5,717,533, and U.S. Pat. No. Re 36,820, which were originally assigned to Methode Electronics, Inc, and are now assigned to Stratos Lightwave, both located in Chicago, Ill., disclose improvements to pluggable transceiver modules. Applicants hereby incorporate by reference U.S. Pat. Nos. 6,570,768, 5,879,173, 5,864,468, 5,734,558, 5,717,533, and Re 36,820.
Due to current designs and specifications, conventional optoelectronic transceiver modules are not compatible with video circuitry or connectors. For example, video subassemblies typically require different connectors, such as ST or BNC connectors. Moreover, video subassemblies commonly utilize unidirectional signals, and thus do not always require a bidirectional signal interface as provided by transceiver modules. Furthermore, a conventional transceiver module can only be installed into a host device specifically designed to receive that specific transceiver module.
Additionally, a video signal typically includes pathological problems, which a conventional transceiver module would be unable to accommodate. Most transmitters in optical modules have an automatic power control (APC) circuit that keeps the optical power output at a set level. These circuits assume incoming data will have a constant average duty cycle of about 50% over a period of time. Such a time period is usually in the range of 1 millisecond (ms). Since the pathological condition may last for about 50 ms, the laser driver of the optical transmitter would be adjusted too high or too low, depending upon the duty cycle of the signal. A detailed explanation of “Pathological Conditions in Serial Digital Video Systems” can be found in the publication having said title by SMPTE Engineering Guideline, Number EG 34-1999, by the Society of Motion Picture and Television Engineers approved and published Jan. 15, 1999, which is hereby incorporated by reference.
Accordingly, there is a need for a small, pluggable optical/electrical interface module that has the advantage of a conventional, pluggable, optical/electrical transceiver module, but in addition, the module is compatible with video circuitry and numerous video connector interfaces.